You are unable to block a range of IP's using either 'block external host' from the Network > Incoming firewall page, or using the Advanced Firewall module-'incoming block'. The rules appear to be added according to the webconfig but no modification is made to the iptables rules
Blocking single hosts works just fine, the syntax tested for source ip is 192.168.1.0/24
Creating the rule manually appears to work just fine as a work around,
iptables -I INPUT -s 192.168.1.0/24 -j DROP
It is of minor significance as the firewall drop's all incoming packets by default, but useful for an explicit drop to prevent a group of IP's accessing your services.
